Traffic doors are two-way swinging doors commonly used in industrial and commercial establishments. The doors are normally biased to the closed position and can be swung to the open position manually or by impact with material handling equipment, such as fork lift trucks, hand trucks, shopping carts, etc. Conventional commercial plastic traffic doors are used in a variety of retail operations, such as supermarkets, convenience stores, and restaurants.
Traffic doors are well known. For example, U.S. Pat. Nos. 3,979,872 to Gilchrist et al., 3,854,263 to Eckel, and 4,397,117 to Shipp all disclose typical prior art traffic doors. It is necessary to design and manufacture prior art traffic doors with sufficient strength and resiliency to withstand impact during opening. These doors typically consist of an internal framework, two oppositely facing door face panels and internal sound insulation. The manufacturing costs associated with prior art traffic doors have been high because of the impact resistance requirements and the method of assembling the doors.
The assembly of a typical prior art traffic door begins by placing a first rectangular plastic door face panel on a supporting work table, and then adhesively bonding to that door face panel a plurality of rectangular honeycombed struts or frame members so as to form a rectangular framework, with one or more of the frame members being disposed cross-wise so as to subdivide the area encompassed by the framework into two or more compartments. The frame members are usually made of wood or are extruded rubber or plastic parts. This initial series of steps includes the need to prepare the opposite sides of the frame members, and preferably also one surface of the two door face panels, for adhesive bonding of the door face panel to the frame members. This preparation normally includes application of adhesive to both the framework and the two door face panels.
Next baffling inserts comprising a material that can act as a sound-absorbing and/or an impact absorbing medium are placed in the open areas or compartments demarcated by the frame members. By way of example, the inserts may consist of foam rubber, fiberglass or other suitable sound or impact absorbing material.
Thereafter, the second door face panel is placed on and bonded to the framework under mechanical pressure so as to form an integrated door body.
Commercially available impact doors typically have door face panels in the form of sheets of acrylonitrile butadiene styrene polymer (A.B.S.), polyethylene, or polyvinylchloride. In applications where the doors are in close proximity to food or pharmaceuticals, the panels constitute U.S.D.A. and F.D.A.-approved grades of the aforementioned or other like materials.
Often, the doors include a window in the form of an opening that is filled with a pane of transparent material. Usually the panel is secured in place by mechanically fastened means, which may include a surrounding frame. Also a resilient nose or nosing, preferably made of a suitable elastomer such as a synthetic rubber, is attached to one longitudinal side of the door, either before or after the panels and frame members are adhesively bonded together. The nose serves as a compliant edge for the door so that when two such doors are mounted in a doorway, the compliant edges engage one another and function as a seal and also as a door edge protector.
A stile is mounted to the other longitudinal side of the door, opposite the nose. Associated with the stile is an external metal mount which is fastened to the two plastic door panels and serves to secure the stile to the door body. The mount also serves to support a circular pivot shaft. A typical prior art stile is solid and extends the length of the door. Its outer longitudinal edge is shaped to provide a circularly curved groove for receiving the circular pivot shaft. Prior art stiles have been made of wood or aluminum, while usually the pivot shaft is made of steel or aluminum.
Door-pivoting hardware, typically consisting of a lower bearing for the pivot shaft and at least a portion of a door cam assembly, is mounted to the foregoing door assembly to complete the manufacturing process.
In addition the door face panels of prior art traffic impact doors commonly are provided with bumpers and wear panels to provide increased impact resistance and longer door life. The bumpers and wear panels may be made of various materials, e.g., plastic, rubber or metal. Typically bumpers are formed of a stiff plastic (e.g., polyethylene) or a hard rubber sheet material and are surface mounted to the plastic door face panels using mechanical fasteners. Plastic bumpers can be molded in colors to match the color of the door face panel; however an exact color match is difficult or costly to obtain.
Although the above described prior art process yields a door of sufficient strength and resiliency to survive the impact of trucks, carts, etc., it suffers from the fact that it involves extensive use of adhesives which require safe use procedures and substantial curing times, as well as presenting critical disposal problems. Moreover, the process requires a considerable amount of manual labor, resulting in high manufacturing costs. Typically preparing the components for adhesive bonding, the adhesive application, and the adhesive curing aspects of this assembly process take from 12 to 24 hours to complete, with several workers being involved in the process. Likewise, considerable time and labor are required to assemble the stile, metal mount and associated hardware. Manufacture and sale of prior art traffic impact doors of the type described above suffer from still other limitations known to persons skilled in the art. Thus, for example, if the nosing becomes worn or damaged during use, it usually is necessary to replace the entire door. Also the metal mounts are exposed, and this negatively affects the aesthetic character of the doors. To improve the aesthetics, additional plastic sheets may be applied to the outer surfaces of the door to cover the exposed metal external mount. However, this approach involves increased costs and also makes it difficult to produce a single color door.